Alkylation of aromatic compounds



'[ bons.

Patented Nov. 24, 1942 ALKYLATION OF AROMATIC CODTPOUNDS LouisSchmerling. Chicago, Ill., assignor to Unlversal Oil Products Company,Chicago, 111., a corporation of Delaware No Drawing. Application August16, 1941, Serial No. 407,223

14 Claims. (Cl. 260-671) This invention relates .to a process for the atreatment of aromatic compounds to produce higher molecular weight alkylderivatives there- 01'. More specifically the process is concerned witha method of alkylating aromatic hydrocarbons by olefinic hydrocarbons inthe presence of a particular type of catalyst to produce monoalkylatedand poly-alkylated aromatic hydrocarbons.

In one specific embodiment the present invention comprises a process forproducing alkylated aromatic hydrocarbons which comprises subjecting anaromatic hydrocarbon and an olefinic hydrocarbon to contact underalkylating conditions in the presence of a solution comprisingessentially aluminum chloride dissoved in a chloronitroparafiin. v

Aromatic hydrocarbons, such as benzene, toluene, other alkylatedbenzenes, naphthalene, alkylated naphthalenes, other poly-nucleararomatics, etc., which are alkylated by oleflnic hydrocarbons ashereinafter set forth, may be obtained by the distillation of coal, bythe dehydrogenation of naphthenic hydrocarbons, by the cyclization ofaliphatic hydrocarbons, and by other means.

Aliphatic olefinic hydrocarbons utilizable for all-:ylating aromatichydrocarbons are either normally gaseous or normally liquid and compriseethylene. propene, butenes, and higher, normally liquid homologs, thelatter including various polymers of normally gaseous olefinic hydrocar-Diolefins, cyclic olefins, and other polyiolefins may also be made toreact with aromatic hydrocarbons, but generally under differentconditions of operation from those employed in the 'alkylation ofaromatic hydrocarbons with noncyclic and branched-chain olefins.Aliphatic olefinic hydrocarbons utilizable in the present process areobtained from any source and comprise products of catalytic and thermalcracking of oils, those obtained by dehydrogenating the correspondingparafiinic hydrocarbons, by dehydrating alcohols, or by polymerizationof normally gaseous olefinic hydrocarbons.

Catalysts suitable for use in the process of the present inventioncomprise solutions of aluminum chloride in a chloronitroparaffin andparticularly in a 1-chloro-1-nitroparafiin of whichl-chloro-Lnitropropane is representative. The differentchloronitroparafllns which may thus be employed for producing solutionscontaining aluminum chloride utilizable as catalysts in the presentprocess, are not necessarily equivalent in that somechloronitroparafiins are, for this purpose, more suitable than others.

Some of the chloronitroparafiins and a few of their physical propertiesare given in the following table for purposes of reference.

chlorom'tro- TabZe.Some propertzes of some paraflins SpecificChloronitroparaiiin B. P., "G gravity at C.

Chloronitromethane 122 l. 47 l-chloro-l-nitro-ethane.. 124 1. 252-chloro-l-nitro-ethane 173 l. 41 l-chloro-l-nitropropanei 143 1.2-cl1loro-l-nitropropane 172 l. 24 3-chloro-l-nitropropane. 197 lv 26z-chloroi-nitropropauel 133 l. 18 l-chloro-2-nitropropanc. 172 1.20l-chloro-2-nitrobutane v 190 1. l6 1cblorol-nitro-2-methylpropane 151 l.15 lchloro-Z-nitro-2-metbylpropane a. 181 l. 18

Chloronitroparafflns utilizable in the process of this invention mayhave the chloro and nitro groups attached to the same carbon atom or todifierent carbon atoms. Thus, chlorination of a nitroparaflin in basicsolution yields a l-chlorol-nitroparailin while chlorination of a verydry liquid nitroparafiin yields 1-chloro-2(or 3)- nitroparafiins. Thedifferent chloronitroparaflins, however, are not necessarily equivalentin their suitability as solvents for aluminum chloride.

Aluminum chloride dissolves readily in 1- chloro-l-nitropropane at about20 C. yielding a clear orange-colored solution. However, if the solventis kept at about 0 C. during the slow addition of substantiallyanhydrous aluminum chloride, 2. deep yellow-colored solution resultswhich becomes orange-colored on warming to about 20 C. Thechloronitroparaffin which has a relatively high dissolving power foraluminum chloride thus produces a solution which is generally misciblewith an aromatic hydrocarbon as in the case of benzene, and thechloronitroparaffin may thus be said to serve as a solutizer fordispersing aluminum chloride in the aromatic hydrocarbon being subjectedto alkylation. Aluminum chloride so dissolved or dispersed in a mixtureof a chloronitroparafiin and an aromatic hydrocarbon is in intimatecontact with the olefin added to said alkylation reaction mixture sothat 1 molecular proportion of aluminum chloride can catalyze thealkylation of many molecular proportions of aromatic hydrocarbon.Essentially the same, solutizing effect is observed when any other orderof mixing is used for the aromatic hydrocarbon aluminum chloride, andehloronitroparafhn. The particular chloronitroparafiin chosen assolutizer for aluminum chloride is also dependent upon the nature andproportions of the hydrocarbons being reacted, the conditions ofoperation, and other factors.

When aluminum chloride in the form of a solid is used as catalyst in thealkylation of aromatic hydrocarbons by olefinio hydrocarbons, theformation of sludge-like material upon the surface of the aluminumchloride used decreases its catalytic activity and ordinarily makes itnecessary to withdraw the sludge-like material and to add fresh aluminumchloride in order to proceed with the alkylation. However, whenalkylating with aluminum chloride dissolved in a chloronitroparafiin,such as a l-chloro-l-nitroparaflin, the catalyst is substantially in theform of a solution which is contacted readily with the reactingaromatichydrocarbons and olefins. Thus, a relatively high speed of alkylation isobtained with a small quantity of aluminum chloride becausesubstantially all of the aluminum chloride so in troduced into thereaction mixture, is available for catalyzing the reaction, a conditionentirely difierent from that which exists with solid aluminum chloridecatalyst as then only the aluminum chloride on the surface of theparticles can be contacted with the reacting hydrocarbons.

In accordance with the present invention, the alkylation of an aromatichydrocarbon by an olefinic hydrocarbon is preferably carried out in thepresence of a solution of aluminum chloride in a chloronitroparafiin ata temperature of from about -25 to about 75 C. and under a pressure offrom substantially atmospheric to approxi-' mately 100 atmospheres. Theexact temperature employed in a given alkylation depends upon theproperties of the aromatic and aliphatic hydrocarbons undergoingreaction. In order to ob tain relatively high yields of most alkylatedaromatic hydrocarbons, it is desirable to have present from about 1 toabout 40 molecular proporw tions of aromatic hydrocarbon to 1 molecularproportion of olefinic hydrocarbon.

In general a higher molecular proportion of aromatic hydrocarbon toolefinic hydrocarbon is employed with a normally liquid olefin than witha normally gaseous olefin because of the fact that the higher molecularweight olefins, particularly those boiling higher than pentenes,generally undergo depolymerization prior to or simultaneouslywith'alkylation. Thus 1 molecular proportion of di-isobutene reacts with2 molecular prowhilean olefinic hydrocarbon or a hydrocarbon fractioncontaining olefinic hydrocarbons is added thereto preferably togetherwith a relatively small amount of hydrogen chloride to effect formationof alkylated aromatic hydrocarbons of higher molecular weight than thearomatic hydrocarbon charged to the process. Only as much aluminumchloride-chloronitroparafiin solution is .added as is required forcatalyzing the alkylation at a desired rate, and the alkylation may thusbe catalyzed by the use of a relatively small quantity of aluminumchloride.

Alkylation products obtained as hereinabove' scribed.

substantially non-reactive liquid solvent.

pressure employed in such a continuous alkylaportions of benzene toproduce 2 molecular proportions of tertiary butyl benzene. To assist incatalyzing the alkylation reaction from about 0.05 to about 5% by weightof hydrogen chloride may be added to the mixture of aromatic andolefinic hydrocarbons being subjected to contact with the solution ofaluminum chloride in a chloronitroparaffin. It may also be desirable tohave hydrogen present in a quantity of not more than about 10 mole percent of the total aromatic and aliphatic hydrocarbons charged.

In effecting reaction between aromatic hydrocarbons and an alkylatingagent as an olefinic or an olefin-producing substance according to theprocess of the present invention, the exact method of procedure varieswith the nature and proportions of the reacting constituents. A simpleprocedure utilizable in the case of an aromatic hydrocarbon which isnormally liquid (or if solid is readily soluble or dispersable in achloronitroparaffin or other substantially inert liquid) and a normallygaseous or liquid olefinic hydrocarbon consists in contacting thearomatic and olefinic hydrocarbons with a solution of aluminum chloridein a chloronitroparaiiin using either batch or continuous operations.Thus in batch type treatment a solution of aluminum chloride in achloronitroparafiin is charged to a reactor containing aromatichydrocarbon and the reaction mixture is then stirred or otherwiseagitated tion treatment are within the indicated limits but theparticular conditions employed in any given alkylation vary with themolecular weights and reactivities of the aromatic and olefinichydrocarbons charged, the concentration and activity of the catalystsolution, and other factors.

It is generally advantageous to dilute the olefinic hydrocarbon with aportion of the aromatic hydrocarbon and to introduce theolefin-containing mixture at a plurality of points throughout thereaction zone rather than to commingle all of the olefinichydrocarbon-containing fraction with the aromatic hydrocarbon prior totheir introduction to the catalytic alkylation zone. In

this way a relatively high ratio of aromatic hy-"= drocarbon to olefinichydrocarbon is readily maintained, alkylation is thereby favored, andolefin polymerization is kept relatively low. The reaction mixtureobtained from such a continuous treatment is then commingled withsufiicient water to decompose the remaining aluminum chloride, theliquid product is dried and distilled to separate unconverted aromatichydrocarbon, alkylated aromatic hydrocarbons, and thechloronitroparaflln solvent. Unconverted and incompletely convertedaromatic hydrocarbons and the recovered chloronitroparafiin solvent arerecycled to further use in the process.

The following example is given to illustrate the character of resultsobtained by the use of the present process although the data presentedare from a selected case and are not introduced with the intention ofunduly restricting the generally broad scope of the invention.

' 5 parts by weight of aluminum chloride dissolved at 0 C. in 10 partsby weight of l-chlorol-nitropropane forming a yellow-colored solutionwhich turned orange in color on warming to about C. and then became deepred upon addition of 80 parts by weight of benzene. The resulting redsolution was placed in a reactor surrounded by a water bath and propanewas passed therethrough at a relatively slow rate. The absorption ofpropene was kept at about 35 C. and during 4 hours 28.5 parts by weightor propene reacted and a reaction mixture was obtained consisting of anupper hydrocarbon layer and a heavier lower layer. The latter material,which amounted to 9 parts by weight, was a browncolored fluid whichreacted vigorously with water. The hydrocarbon layer after washing withwater and drying, amounted to 105.6 parts by weight (119 volumes) andwas separated by distillation into the following fractions: unconvertedbenzene, 47 parts by weight; 1-chloro-1-nitropropane, 6 parts by weight;isopropyl benzene, 30

" parts by weight; fraction 163--204 C., 35 parts by weight;di-isopropyl benzene, 18 parts by weight; and higher boiling material,13 parts by weight.

The nature ofthe present invention and its commercial utility can beseen from the speciflcation and example given, although neither sectionis intended to limit its generally broad scope.

I claim as my invention:

1. A process for producing alkylated aromatic compounds which comprisessubjecting an arcmatic compound and an olefinic hydrocarbon to contactunder alkylating conditions in the presence of a catalyst comprisingessentially aluminum chloride dissolved in a chloronitroparaffin.

2. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hyrocarbon and an olefinic hydrocarbonto contact under alkylating conditions in the presence of a catalystcomprising essentially aluminum chloride dissolved in achloronitroparaffin.

3. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbonto contact at a temperature of from about to about 75 C., in thepresence of a catalyst comprising essentially aluminum chloridedissolved in a chloronitroparaffin.

4. A process for producing alkylated aromatic i hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbonto contact at a temperature of from about 25 C. to about 75 C. under apressure of from substantially atmospheric to approximately 100atmospheres in the presence of a catalyst comprising essentiallyaluminum chloride dissolved in a chloronitroparaffin.

5. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon, an olefinic hydrocarbon,

. and hydrogen chloride to contact at a temperature of from about -25 C.to about 75 C. under a pressure of from substantially atmospheric toapproximately 100 atmospheres in the presence of a catalyst comprisingessentially aluminum chloride dissolved in a chloronitroparaffin.

6. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon, an olefinic hydrocarbon,and

hydrogen to contact at a temperature of from about 25 to about 75 C.under a pressure of pheric to approximately 100 atmospheres in thepresence of a catalyst comprising essentially aluminum chloridedissolved in a chloronitroparaifin.

8. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and a normally gaseousolefinic hydrocarbon to contact at a temperature of from about 25toabout 75 Qunder a pressure of from substantially atmospheric toapproximately 100 atmospheres in the presence of a catalyst comprisingessentially aluminum chloride dissolved in a chloronitroparafiin.

9. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and a normally liquidolefinic hydrocarbon to contact at a temperature of from about 25 toabout C. under a pressure of from substantially atmospheric toapproximately atmospheres in the presence of a catalyst comprisingessentially aluminum chloride dissolved in a chloronitroparafiin.

10. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbonto contact at a temperature of from about -25 to about 75 C. under apressure of from substantially atmospheric to approximately 100atmospheres in the presence of both aluminum chloride and aI-chIQro-Imitroparamn.

11. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbonto contact at a temperature of from about -25 to about 75 C. under apressure of from substantially atmospheric to approximately 100atmospheres in the presence of both aluminum chloride andl-chloro-l-nitropropane.

12. A process forproducing alkylated benzenes which comprises subjectingbenzene and an olefinic hydrocarbon to contact at a temperature of fromabout -25 to about 75 C. under a pressure of from substantiallyatmospheric to approximately 100 atmospheres in the presence of bothaluminum chloride and a l-chloro-l-nitroparafiin.

13. A process for producing alkylated benzenes which comprisessubjecting benzene and an olefinic hydrocarbon to contact at atemperature

